This patch adds the DBX500 PRCMU Timer driver as a clocksource
and as sched_clock.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NMattias Wallin <mattias.wallin@stericsson.com>
Signed-off-by: NJonas Aaberg <jonas.aberg@stericsson.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>